Rock drilling device



May 4, 1965 E. o, PERssoN ROCK DRILLING DEVICE IN VEN TOR. /-Qf/mw BY n United States Patent Office 3,181,434 Patented May 4, 1h65 3,181,434 RCK DRILLENG DEVHCE Erik Giov Persson, Naiden, Sweden, assigner to Torsten Neldas Filed Nov. 27", 1962, Ser. No. 240,217 4 Claims. (Ci. 952-167) The present invention refers to a rock drilling device in which a drill holder is connected to a slide reciprocating in a housing by aid of a driving rod which from outside is given a reciprocating movement and slidably eX- tends into the slide.

In already known drilling devices the reciprocating movement of the driving rod is transferred to the slide by means of two helical springs arranged to act in opposite direction that are compressed between abutments on the driving rod and the slide, respectively. The movement of the slide in the housing is thereby dampened and the slide is moved in the same direction as the driving power transmitted from the driving rod to the slide4 This way of transmitting and dampening the driving power, however, has many disadvantages. lt is thus difficult to impart the necessary number of strokes per unit of time to a rock drilling device driven in this manner. Furthermore, the springs must be big and heavy if they are to possess suiiicient strength and lifetime which increases the dimensions and manufacturing costs of the rock drilling device. This is a great disadvantage, especially as rock drilling devices according to the present invention mainly are intended for use in drilling contrivances for holes with large diameters, said contrivances containing a number of rock drilling devices.

According to the invention the above disadvantages are mainly removed by the fact that the movements of the driving rod are transmitted to the slide and the movements of said slide thus imparted are dampened and the slide returned lby aid of pressure iiuid cushions which in the direction of movement of said driving rod and said slide are enclosed in spaces between said driving rod and said slide and between said slide and said housing, respectively, each of said spaces being sealed s-o as to be fluid tight in all directions during the main part of the strokes of the driving rod and the slide, respectively, from their center positions in the direction towards each space.

The part of the driving rod extending into the slide is thereby preferably provided with a disc-like iiange which is slidabiy arranged in a cylindrical cavity in the slide in fluid tight relation to the wall of said cavity. The spaces for the pressure fluid cushions for the transfer of the movement of the driving rod are provided at both sides of the disc-shaped ange.

In a similar way that part of the slide enclosing said cylindrical cavity has the form of a piston-like extension which is slidably arranged in a cylindrically formed chamber in said housing in fluid tight relation to the wall of same, the spaces enclosing the pressure uid cushions for damping the movement of the slide and returning same being positioned in the cylindrical chamber at bothl sides of the piston-like extension ofthe slide.

A further advantage of the transfer of the driving power and dampening effect of the moving parts according to the invention is achieved by the fact that a pressure fluid cushion has a more advantageous spring characteristic than an ordinary helical spring. The latter forms a mainly linear spring curve i.e., the spring power is directly proportional to the Acompression of the spring. By using a pressure fluid cushion the increase of the spring power per unit of spring compression, however, becomes greater the greater the total spring compression. The result therefore is that the vis viva of the movable parts at the beginning of the impact movement does not decrease as much as when helical springs are used. Furthermore, the harmonic oscillation movement of the driving rod will not be distorted to such a high extent when using dampening by means of pressure iluid cushions as would be the case when helical springs are used.

An embodiment of the invention will hereinbelow 'be described in detail with reference to the attached drawing which is an axial section showing a rock drilling device according to the invention.

The rock drilling device is driven by a driving device, not shown, preferably in the form of a link and eccentric mechanism which imparts a reciprocal harmonic swinging movement to a driving rod 1. Said driving rod 1 extends slidably through a tubular slide 2 which at the end thereof facing away from the driven end of the driving rod 1 is rigidly connected to a drill holder 3 in which a rock drill of known construction is attac-hable. If desired the slide 2 and the drill holder 3 can be made in one piece.

The driving r-od 1 extends slidably through .the boring of the slide 2, with packing means being arranged between the driving rod and the slide. On the portion of the driving rod 1 enclosed in the slide Z a disc-'shaped ange 4 is provided, which iiange is recipnocably slidable in a cylindrical cavity S formed by an extension 6 of 4said slide. Between the edge of the disc-shaped flange 4 and the inner wall of the -cavity 5 packing rings 7 are arranged, the purpose of which is to provide a iluid tight seal 'between spaces 8 and 9 of the cavity 5 located on each side of the disc-shaped vflange 4. One or more uid passages extend through the wall of the cavity 5 perpendicularly to said wall.

The tubular part of the slide 2 is slidably movable in a tubular housing 11, while the extension 6 of the slide enclosing the cavity 5 is slidable in `a cylindrical chamber 413 forming a part ofthe housing with greater inner diameter. The tubular parts yof the slide 2 are sealed against the inner wall `of the housing 11 by means of packing rings.

. The extension 6 forms a cylindrical piston and the chamber 13 surrounds same as a cylinder, the extension dividing said chamber into two cylinder chambers 14 and 15 on each side of said extension 6. Close to the end surface of the extension 6 packing rings 16, 17 are provided between the outer wall of the extension 6 and the inner wall of the chamber 13. Two pressure iiuid passages 18 and 19 extend perpendicularly through the wall of said chamber 13 in such axial positions that the pistonlike extension 6 in its movement up and down in the chamber 13 uncovers one of the openings to the chamber just before slide 2 reaches the end position in its direction of movement. The intention herewith will be further explained in the following.

The rock drilling device described above is as a whole insertable in a tubular holder 20 in which it is retained by means of bolts 21 extending through a flange 22 of the housing. The holder 20 surrounds the housing 11 and is sealed by packing rings. The rock drilling device thus can easily be inserted into and removed from the holder 20. Spaces for introduction of pressure uid and lubricant are conveniently provided by annular packing rings which bridge the distance between the inner diameter of the holder 20 and the outer diameter of the housing 11 i axiallyenclosed between packing rings intermediate said two members. The pressure fluid passages 1S and 19 in the wall of the chamber 13 also open into the space 24 and extend to another annular space 25 between the inner Wall of the chamber 13 and the outer wall of the extension 6 of the slide 2, said last-mentioned space 25 being axially enclosed by the packing rings 16 and 17. The outer end of the pressure Huid passage inthe wall of the cavity S also opens into this space 25.

' When the driving rod 1 is reciprocated by its outside driving mechanism the disc-shaped flange 4 is reciprocated in the cavity 5 and .in doing so the trailing space 8 or 9 of the cavity 5 is at each stroke put into communication with pressure fluid passage 1G via the passages 23, space 24,V passages 18, 19, space 25 and a pressure is built up in the spaces 8 and 9. The pressure lluid cushions formed thereby transmit the movements of the driving rod 1 on to the slide 2 wh-ich thus is given a reciprocating movement in the housing 11. During this movement the extension 6 of the slide 2 in each stroke uncovers the oriiice of the trailing passages 18 and 19, respectively, so that pressure fluid is introduced into said passage 18 or 19 via the passage 23 and the spac-e 24 and a pressure is built up in corresponding cylinder chambers 14 and 15, respectively, thus forming fluid cushions for the damping of the movement of the slide 2.

Thus the pressure fluid for transfer and damping is only introduced through passage 23 and flows through space 24, passages 1S, 19, space 25 and passage 10V and is Vdistributed to the spaces intended for the lluid by the relative movements of the parts ofthe drilling device. At the same time the proper air or iiuid pressure is maintained in these spaces as each of them during each stroke is put into communication with the pressure iluid source so that leaking uid, if any, isv compensated.

To prevent the drill, either by a failure in the pressure fluid system or when the drilling operation is to be ended and the feeding of pressure iluid is interrupted, from being brought into engagement with the drilling spot, the drilling device according to the invention is provided with means which automatically lifts the slide 2 .and the drill holder 3 out of engagement with the drilling hole.

This means comprises a second cylindrical chamber 26 in the housing 11 coaxial with the chamber 13 and sur rounding the tubular part of the slide 2. In the annular space formed between the wall of the chamber 26 and the slide 2 la piston member 27 is slidable and sealed both against said wall and the slide. The piston member 27 is annular and at one of its end surfaces an annular groove 28 extends axially almost up to the opposite end surface. This annular groove encloses a compres-sion spring 29 one end of which abuts against the bottom of the groove while the other end rests against one end surface of the chamber. When the drilling operationfstarts pressure fluid is forced into the chamber 26-above the unbroken end surfaceof the piston member and said pressure fluid forces the piston member against the action of the spring 29 into abutment with the end surface of the chamber supporting said spring 29. When the drilling operation is interrupted, the pressure in the chamber 26 decreases and the spring 29 forces the piston member in a direction opposite Vfrom the drilling direction. This displacement of the piston member is without opposition until the piston member engages a ring flange 30 on the tubular part of the slide 2. When the displacement of the piston member 27 continues the slide is carried along by means of thering flange 30 and indoing so the drill is displaced so that the drilling contrivances can be moved in `the hole without the drill preventing such movement. When the drilling operation continues pressure iluid again enters the chamber 26 and depresses the piston member 27 against the action of the spring 29 so that the drill by its own weight is returned to working position.

' The drilling device described above is preferably used in drilling contrivances for making large-holes in the oneness ground, in which a number of drilling devices are arranged around the outer surface of a conical drilling head and attack the walls of the hole at an angle relative to the main drilling direction. The above described device for lifting the drill out of engagement can be replaced by a mechanism turning the drill around its axis so that the chisel-formed cutting edge thereof occupies a position parallel to the tangent of the drill hole. Thus the outer edgey of the chisel-formed cutting edge in drilling position is brought out of engagement with the Wall of the hole and the drilling head is free to be lifted out of the drill hole.

The driving mechanism is preferably connected to the Vdriving rod 1 by means of a clutch, preferably a hydraulic clutch, which is constructed in such a way that it is not engageduntil the pressure fluid has reached the pressure necessary for the drilling operation.

As drilling devices of theV type described often have to work under very hard conditions, for instance always surrounded by scavenging water, very high demands are put upon the sealing between the diiferent elements of the device and the lubrication of the elements movable relatively to another.

In the embodiment described all sealings are annular. The sealing between every two elements of the drilling device is formed by one or more pairs of packing rings. These pairs of packing rings form the axial limits of the annular spaces between the elements in form corresponding to the spaces 24 Iand 25. According to the invention oil under pressure is introduced into these annular spaces, the oil preferably being delivered through the inlet passage 31 formed in the Wall of the holder 2t) and into one of these spaces. From the last-mentioned space the oil under pressure is there-after distributed through passages in the housing 11, the slide 2 and the driving rod 1 tothe different spaces. between the pairwise arranged packing rings considerably contributes to achieve a satisfactory seal both against Water and foreign matters penetrating from outside as well as against pressure fluid flow between the different spaces for fluid. At the same time a very good lubrication of the different sliding surfaces of the device is provided when said oil filled spaces are reciprocated over said surfaces. The pressure lluid leaking into the oil filled spaces or transferred thereto when the packing rings on the disc-shaped flange or the piston-like extension 6 travel past the fluid passages 1G and 18, 19, respectively, is vented together'with the oil stream being disposed through one or more outlet passages 32, 33.

As shown above the invention provides a constructively simple drilling device showing the advantages mentioned in the preamble, which drilling device is capable to work with a very high number of strokes per unit of time. The

embodiment described and shown must not be considered limiting for the invention but only be regarded as an example of how the invention can be realized.

What is claimed is:

1. A rock drilling device comprising a tubular casing, a tubular housing mounted inside said casing, means delining an annular space between said housing and said casing, sealing means carried between said casing and said housing at points spaced axially therealong for maintaining said annular space airtight, axially spaced annular means projecting radially inwardly rom said tubular housing defining a cylindrical chamber therein, a drill holder extending axially into said housing, said drill holder having an enlarged piston portion thereon Vslid-ably received in the cylindrical chamber of said housing; at least a part of the piston portion of said drill holder being hollow dening a cylindrical chamber within the piston portion, a drill driving rod extending axially into said drill holder, said drill driving rod having an enlarged piston portion slidably received in the cylindrical chamber of said drill holderysealing means received between said driving rod piston, and said drill holder cylindrical The high pressure oil-introducedchamber and between said driving rod and said drill holder for maintaining the space above and below the piston portion ofthe driving rod airtight; sealing means between said drill holder piston and said cylindrical housing chamber and between said drill holder and said tubular housing for maintaining the space above and below the piston portion of the drill holder airtight; means for supplying a pressurized iiuid to the space above and below the piston portions of the drill holder and the drill driving rod, said pressure fluid being used for transmitting the reciprocal movement of said driving rod to said drill holder and dampening the reciprocal movement of said drill holder.

2. A rock drilling device comprising a tubular casing, a tubular housing mounted inside said casing, means defining an annular space between said housing and said casing, sealing means carried between said casing and said housing at points spaced axially therealong for maintaining said annular space airtight, axially spaced annular means projecting radially inwardly from said tubular housing dening a cylindrical chamber therein, a drill holder extending axially into said housing, said drill holder having an enlarged piston portion thereon slidably received in the cylindrical chamber of said housing; at least a part of the piston portion of said drill holder being hollow defining a cylindrical chamber within the piston portion, a drill driving rod extending axially into said drill holder, said drill driving rod having an enlarged piston portion slidably received in the cylindrical chamber of said drill holder; sealing means received between said driving rod piston and said drill holder cylindrical chamber and between said driving rod and said drill holder for maintaining the space above and below the piston portion of the driving rod airtight; sealing means between said drill holder piston and said cylindrical housing chamber and between said drill holder and said tubular housing for maintaining the space above and below the piston portion of the drill holder airtight; means defining an opening into said cylindrical chamber of the drill holder generally radially thereof intermediate the ends of the chamber, the piston portion of the driving rod being movable between a first position wherein the opening communicates with the space defined between one end of the piston and one end of the cylindrical drill holder chamber and a second position wherein the opening communicates with the space dened between the other end of the piston and the other end of cylindrical drill holder charnber whereby pressurized fluid is alternately communicable to said spaces in the cylindrical drill holder charn- Cil ber to replenish fluid leaking therefrom during reciprocation of said piston; means defining an opening into said cylindrical housing chamber generally radially thereof, the piston portion of the drill holder being movable between a iirst position wherein the opening communicates with the space defined between one end of the piston and one end of the cylindrical housing chamber and a second position wherein the opening communicates with the spaces defined between the other end ot the piston and the other end of the cylindrical housing chamber whereby pressurized iiuid is alternately communicable to said space in the cylindrical housing chamber to replenish fluid leaking therefrom during reciprocation of said piston; and means defining an opening into said annular space between said housing and said casing, said pressure fluid being used for transmitting the reciprocal movement of said driving rod to said drill holder and dampening the reciprocal movement of said drill holder.

3. A rock drilling device according to claim 2 wherein the sealing means between members of the device cornprises a plurality of annular sealing rings arranged in axially spaced pairs and means for introducing oil under pressure into the clearance thus defined between the sealing rings for lubrication of the sliding surfaces and to improve the sealing effect.

4. A rock drilling device according to claim 1 wherein the tubular housing defines a second cylindrical chamber coaxial with the other cylindrical housing chamber, said second chamber enclosing a spring biassed :against an annular piston member surrounding the upper portion of said drill holder, said drill holder having an annular collar projecting radially therefrom above said piston member, means defining an opening into said second cylindrical chamber and means for introducing iiuid under pressure to said second chamber during operation of the drilling device for compressing the spring and holding the annular piston member below said collar and means for decreasing the fluid pressure in the second chamber when the drilling device is not operating whereby said spring contacts the annular collar of the drill holder and lifts the drill holder away from the work surface upon which the device is operating.

References Cited by the Examiner UNITED STATES PATENTS 2,854,954 lll/58 Howze 92-63 3,051,237 8/62 Liles et al 74-583 FRED E. ENGELTHALER, Primary Examiner. 

1. A ROCK DRILLING DEVICE COMPRISING A TUBULAR CASING, A TUBULAR HOUSING MOUNTED INSIDE SAID CASING, MEANS DEFINING AN ANNULAR SPACE BETWEEN SAID HOUSING AND SAID CASING, SEALING MEANS CARRIED BETWEEN SAID CASING AND SAID HOUSING AT POINTS SPACED AXIALLY THEREALONG FOR MAINTAINING SAID ANNULAR SPACE AIRTIGHT, AXIALLY SPACED ANNULAR MEANS PROJECTING RADIALLY INWARDLY FROM SAID TUBULAR HOUSING DEFINING A CYLINDRICAL CHAMBER THEREIN, A DRILL HOLDER EXTENDING AXIALLY INTO SAID HOUSING, SAID DRILL HOLDER HAVING AN ENLARGED PISTON PORTION THEREON SLIDABLY RECEIVED IN THE CYLINDRICAL CHAMBER OF SAID HOUSING; AT LEAST A PART OF THE PISTON PORTION OF SAID DRILL HOLDER BEING HOLLOW DEFINING A CYLINDRICAL CHAMBER WITHIN THE PISTON PORTION, A DRILL DRIVING ROD EXTENDING AXIALLY INTO SAID DRILL HOLDER, SAID DRILL DRIVING ROD HAVING AN ENLARGED PISTON PORTION SLIDABLY RECEIVED IN THE CYLINDRICAL CHAMBER OF SAID DRILL HOLDER; SEALING MENS RECEIVED BETWEEN SAID DRIVING ROD PISTON, AND SAID DRILL HOLDER CYLINDRICAL CHAMBER AND BETWEEN SAID DRIVING ROD AND SAID DRILL HOLDER FOR MAINTAINING THE SPACE ABOVE AND BELOW THE PISTON PORTION OF THE DRIVING ROD AIRTIGHT; SEALING MEANS BETWEEN SAID DRILL HOLDER PISTON AND SAID CYLINDRICAL HOUSING CHAMBER AND BETWEEN SAID DRILL HOLDER AND SAID TUBULAR HOUSING FOR MAINTAINING THE SPACE ABOVE AND BELOW THE PISTON PORTION OF THE DRILL HOLDER AIRTIGHT; MEANS FOR SUPPLYING A PRESSURIZED FLUID TO THE SPACE ABOVE AND BELOW THE PISTON PORTIONS OF THE DRILL HOLDER AND THE DRILL DRIVING ROD, SAID PRESSURE FLUID BEING USED FOR TRANSMITTING THE RECIPROCAL MOVEMENT OF SAID DRIVING RODS TO SAID DRILL HOLDER AND DAMPENING THE RECIPROCAL MOVEMENT OF SAID DRILL HOLDER.
 4. A ROCK DRILLING DEVICE ACCORDING TO CLAIM 1 WHEREIN THE TUBULAR HOUSING DEFINES A SECOND CYLINDRICAL CHAMBER COAXIAL WITH THE OTHER CYLINDRICAL HOUSING CHAMBER, SAID SECOND CHAMBER ENCLOSING A SPRING BIASSED AGAINST AN ANNULAR PISTON MEMBER SURROUNDING THE UPPER PORTION OF SAID DRILL HOLDER, SAID DRILL HOLDER HAVING AN ANNULAR COLLAR PROJECTING RADIALLY THEREFROM ABOVE SAID PISTON MEMBER, MEANS DEFINING AN OPENING INTO SAID SECOND CYLINDRICAL CHAMBER AND MEANS FOR INTRODUCING FLUID UNDER PRESSURE TO SAID SECOND CHAMBER DURING OPERATION OF THE DRILLING DEVICE FOR COMPRESSING THE SPRING AND HOLDING THE ANNULAR PISTON MEMBER BELOW SAID COLLAR AND MEANS FOR DECREASING THE FLUID PRESSURE IN THE SECOND CHAMBER WHEN THE DRILLING DEVICE IS NOT OPERATING WHEREBY SAID SPRING CONTACTS THE ANNULAR COLLAR OF THE DRILL HOLDER AND LIFTS THE DRILL HOLDER AWAY FROM THE WORK SURFACE UPON WHICH THE DEVICE IS OPERATING. 